The mechanism of the phosphate transfer process in the enzymic reaction catalyzed by rabbit muscle phosphoglucomutase (PGM) will be investigated by (a) determining whether the active-site metal ion of PGM is directly coordinated with the phosphate group that is transferred in the catalytic process by use of P31-NMR techniques; (b) determining to what extent the coordination geometry of the active Co. PGM complex deviates substantially from the octahedral-like geometry of the active Ni 2 ion and Mn 2 ion complexes of PGM, and to what extent substrate binding alters this geometry; (c) continuing a study of the effect of substrate structure on the efficiency of phosphate transfer in an attempt to decide what are the critical features of the substrate that determine reactivity and how these act to produce up to a 3 x 10 to the 10th power fold increase in transfer rate relative to that with a "bare" acceptor its dimeric nature is important in catalysis; (e) determining whether PGM action is in fact subject to allosteric control, and if so, whether a conformational change accompanying the conversion of phospho enzyme to the dephospho from provides a basis for such control, as suggested by others; (f) determining whether PGM is a good candidate for further mechanistic studies by examining its suitability for X-ray crystallography. Bibliographic references: Burgner, J. W., II, and Ray, W. J., Jr. (1974). A study of Pyruvate-Induced Inhibition in the Dogfish Lactate Dehydrogenase System. Mechanistic Comparison with the Iodination of Pyruvate. Biochemistry 13, 4229-4237.